Ein Migration eines NodeBB-Forums mit MongoDB zu Discourse

As you properly know, NodeBB supports two DB backends, Redis and MongoDB. Discourse importer script supports them both. In this tutorial, we will learn how to migrate NodeBB with MongoDB as DB backend. We will be using NodeBB Importer with mongo adapter. If your NodeBB forum uses Redis as backend then please follow this tutorial which demonstrate the redis adapter.

The plan

  • Preparing the development environment.

  • Export database from production environment.

  • Import the production DB to a Discourse instance.

  • Run the importer script.

What can be migrated

  • Groups
  • Attachments
  • Categories
    • Root Category => Root Category
    • Sub Category & Sub-Sub-Category => Sub-Category
  • Topics & Posts
    • pinned topic => pinned topic
    • locked topic => closed topic
    • topic views
    • upvoted_by
    • styles, mentions, emoji, and attachments.
  • Users (with the following attributes)
    • profile background
    • avatars
    • banned status
    • username
    • name
    • email
    • admin
    • bio
    • group
    • website
    • location
    • joining at

Preparing Local Development Environment

As mentioned in our plan we first need to prepare our development environment. Follow one of these guides to install Discourse itself:

:bulb: Please, consult this guide if you have any problems setting up Discourse server.

Then install MongoDB database server.

Ubuntu-18-04:

$ wget -qO - https://www.mongodb.org/static/pgp/server-4.0.asc | sudo apt-key add -
$ echo "deb [ arch=amd64 ] https://repo.mongodb.org/apt/ubuntu bionic/mongodb-org/4.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.0.list
$ sudo apt-get update
$ sudo apt-get install -y mongodb-org
$ sudo service mongod status

For more details, refer to the official guide

Mac OS:

$ brew tap mongodb/brew
$ brew install mongodb-community@4.0
$ brew services start mongodb-community@4.0
$ brew services status mongodb-community@4.0

For more details, refer to the official guide

Windows 10:

Download the installer and install MongoDB as a Windows service:

https://fastdl.mongodb.org/win32/mongodb-win32-x86_64-2008plus-ssl-4.0.12-signed.msi

Run the cmd with Administrative privileges to check if the mongo server is working properly:

"C:\Program Files\MongoDB\Server\4.0\bin\mongo.exe"

For more details, refer to the official guide.

This environment will be our Discourse server.

Exporting Production Database Dump:

Shut down your NodeBB forum (production server).

$ cd /path_to_nodebb
$ ./nodebb stop

Shut down your database:

$ sudo service mongodb stop

Backup your DB:

$ mongodump --out ~/my_backup_path/

The output of the previous command will be something like this:

2019-08-16T15:17:09.845+0300 done dumping admin.system.users (1 document)
2019-08-16T15:17:09.846+0300 done dumping admin.system.version (2 documents)
2019-08-16T15:17:09.849+0300 done dumping nodebb.sessions (10 documents)
2019-08-16T15:17:09.850+0300 done dumping nodebb.socket.io (215 documents)
2019-08-16T15:17:09.854+0300 done dumping nodebb.objects (1488 documents)

Note that the backup is actually a directory, not just a file.

:bulb: You can check the size of your DB by running use myDatabase then db.stats().dataSize; inside mongo CLI. The returned value will be in bytes.

Backup your forum assets:

$ cd /path_to_nodebb_root_directory/
$ tar -czf ./uploads.tar.gz ./public/uploads

After you have your DB and assets forum you should copy them to Discourse server.

Importing The Database

Now that we have our database we can import it in our local MongoDB instance:

$ mongorestore ~/path_of_my_backup_directory/

For more options, refer to official guide.

Next, you need to extract the uploads.tar.gz so the importer can import the assets:

$ tar xvzf uploads.tar.gz

Running The Importer Script

Now that our database and assets in place we are ready to run our importer script. Before that, we need to edit the NodeBB importer script to fit our needs.

This is the path of your NodeBB uploads folder:

ATTACHMENT_DIR = '/absolute_path/uploads'

Next, we need to tell the importer to use the mongo adapter instead of redis adapter:

adapter = NodeBB::Mongo
@client = adapter.new('mongodb://127.0.0.1:27017/nodebb')

# adapter = NodeBB::Redis
# @client = adapter.new(
# host: "localhost",
# port: "6379",
# db: 14
# )

Run the importer with clean Discourse and mongo gem support:

$ cd ~/discourse
$ echo "gem 'mongo'" >> Gemfile
$ bundle install
$ bundle exec rake db:drop db:create db:migrate
$ bundle exec ruby script/import_scripts/nodebb/nodebb.rb

The importer will connect to the MongoDB instance and migrates everything to Discourse.

After the importer finishes, start Discourse:

$ bundle exec rails server

Start Sidekiq to process the migrated data:

$ bundle exec sidekiq

You can monitor the progress at http://localhost:3000/sidekiq/queues.

Perform a Discourse backup and upload it to your Discourse production server by following this tutorial.

:tada:

If you have any questions about the process I am happy to help.

Happy migration :grinning:

10 „Gefällt mir“

Great work really. While I was trying, I am getting below error. Any idea what I might be doing wrong here?

importing groups
   10 / 10 (100.0%)  [474765 items/min]    
importing top level categories...
    8 / 8 (100.0%)  [437896 items/min]    
importing child categories...
   68 / 68 (100.0%)  [774048 items/min]  
importing users
 5534 / 5534 (100.0%)  [355520 items/min]    
adding users to groups...

importing topics...
Traceback (most recent call last):
	12: from script/import_scripts/nodebb/nodebb.rb:532:in `<main>'
	11: from /home/fsuzer/discourse/script/import_scripts/base.rb:47:in `perform'
	10: from script/import_scripts/nodebb/nodebb.rb:52:in `execute'
	 9: from script/import_scripts/nodebb/nodebb.rb:336:in `import_topics'
	 8: from /home/fsuzer/discourse/script/import_scripts/base.rb:877:in `batches'
	 7: from /home/fsuzer/discourse/script/import_scripts/base.rb:877:in `loop'
	 6: from /home/fsuzer/discourse/script/import_scripts/base.rb:878:in `block in batches'
	 5: from script/import_scripts/nodebb/nodebb.rb:337:in `block in import_topics'
	 4: from /home/fsuzer/discourse/script/import_scripts/nodebb/mongo.rb:71:in `topics'
	 3: from /home/fsuzer/discourse/script/import_scripts/nodebb/mongo.rb:71:in `map'
	 2: from /home/fsuzer/discourse/script/import_scripts/nodebb/mongo.rb:71:in `block in topics'
	 1: from /home/fsuzer/discourse/script/import_scripts/nodebb/mongo.rb:79:in `topic'
/home/fsuzer/discourse/script/import_scripts/nodebb/mongo.rb:100:in `post': undefined method `[]' for nil:NilClass (NoMethodError)

Some field from the topic is empty. Or perhaps the topic query returned nothing.

1 „Gefällt mir“

Can someone help me?

Error: Could not find gem ‘mongo’ in any of the gem sources listed in your Gemfile.

After $ bundle install

This will happen if you skipped this:

Make sure you Gemfile has this line:

gem 'mongo'

Then run:

$ bundle install
1 „Gefällt mir“

Gem

Thanks for your help. But this line already exists in my file. I also did the previous steps informed.

I don’t know if that helps, but when I run gem list mongo it’s not listed.

Your Gemfile sounds weird to me. Please, can you share the whole content?

Your Gemfile is just wrong. It should have another content, just like this:

In addition to:

gem 'mongo'

Hey,

Thanks for the guide! When I run the migration script, this is what I get when the script reaches the point where it imports users:

Traceback (most recent call last):
        21: from script/import_scripts/nodebb/nodebb.rb:532:in `<main>'
        20: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:47:in `perform'
        19: from script/import_scripts/nodebb/nodebb.rb:50:in `execute'
        18: from script/import_scripts/nodebb/nodebb.rb:130:in `import_users'
        17: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:262:in `create_users'
        16: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:262:in `each'
        15: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:274:in `block in create_users'
        14: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:391:in `create_user'
        13: from /home/odyslam/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/core_ext/object/try.rb:15:in `try'
        12: from /home/odyslam/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/core_ext/object/try.rb:15:in `public_send'
        11: from script/import_scripts/nodebb/nodebb.rb:164:in `block (2 levels) in import_users'
        10: from script/import_scripts/nodebb/nodebb.rb:211:in `import_profile_picture'
         9: from /home/odyslam/forum/discourse/lib/upload_creator.rb:45:in `create_for'
         8: from /home/odyslam/forum/discourse/lib/distributed_mutex.rb:14:in `synchronize'
         7: from /home/odyslam/forum/discourse/lib/distributed_mutex.rb:29:in `synchronize'
         6: from /home/odyslam/forum/discourse/lib/distributed_mutex.rb:29:in `synchronize'
         5: from /home/odyslam/forum/discourse/lib/distributed_mutex.rb:33:in `block in synchronize'
         4: from /home/odyslam/forum/discourse/lib/upload_creator.rb:66:in `block in create_for'
         3: from /home/odyslam/forum/discourse/lib/upload_creator.rb:381:in `optimize!'
         2: from /home/odyslam/forum/discourse/app/models/optimized_image.rb:178:in `ensure_safe_paths!'
         1: from /home/odyslam/forum/discourse/app/models/optimized_image.rb:178:in `each'
/home/odyslam/forum/discourse/app/models/optimized_image.rb:179:in `block in ensure_safe_paths!': Discourse::InvalidAccess (Discourse::InvalidAccess)

I managed to bypass this by commenting out the part that uploads profile pictures, that’s not a problem.

Now I get the nil error when importing topics. :frowning:

Traceback (most recent call last):
        12: from script/import_scripts/nodebb/nodebb.rb:532:in `<main>'
        11: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:47:in `perform'
        10: from script/import_scripts/nodebb/nodebb.rb:52:in `execute'
         9: from script/import_scripts/nodebb/nodebb.rb:336:in `import_topics'
         8: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:862:in `batches'
         7: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:862:in `loop'
         6: from /home/odyslam/forum/discourse/script/import_scripts/base.rb:863:in `block in batches'
         5: from script/import_scripts/nodebb/nodebb.rb:337:in `block in import_topics'
         4: from /home/odyslam/forum/discourse/script/import_scripts/nodebb/mongo.rb:71:in `topics'
         3: from /home/odyslam/forum/discourse/script/import_scripts/nodebb/mongo.rb:71:in `map'
         2: from /home/odyslam/forum/discourse/script/import_scripts/nodebb/mongo.rb:71:in `block in topics'
         1: from /home/odyslam/forum/discourse/script/import_scripts/nodebb/mongo.rb:79:in `topic'
/home/odyslam/forum/discourse/script/import_scripts/nodebb/mongo.rb:100:in `post': undefined method `[]' for nil:NilClass (NoMethodError)

In case anyone is interested in the future, I managed to perform the migration. Here are some comments regarding my experience; there are a couple of gotchas in the process.

2 „Gefällt mir“
21: from script/import_scripts/nodebb/nodebb.rb:532:in `\u003cmain\u003e'
        20: from /home/nodebb/discourse/script/import_scripts/base.rb:47:in `perform'
        19: from script/import_scripts/nodebb/nodebb.rb:50:in `execute'
        18: from script/import_scripts/nodebb/nodebb.rb:130:in `import_users'
        17: from /home/nodebb/discourse/script/import_scripts/base.rb:264:in `create_users'
        16: from /home/nodebb/discourse/script/import_scripts/base.rb:264:in `each'
        15: from /home/nodebb/discourse/script/import_scripts/base.rb:276:in `block in create_users'
        14: from /home/nodebb/discourse/script/import_scripts/base.rb:393:in `create_user'
        13: from /home/nodebb/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.4.1/lib/active_support/core_ext/object/try.rb:15:in `try'
        12: from /home/nodebb/.rbenv/versions/2.7.1/lib/ruby/gems/2.7.0/gems/activesupport-6.1.4.1/lib/active_support/core_ext/object/try.rb:15:in `public_send'
        11: from script/import_scripts/nodebb/nodebb.rb:164:in `block (2 levels) in import_users'
        10: from script/import_scripts/nodebb/nodebb.rb:211:in `import_profile_picture'
         9: from /home/nodebb/discourse/lib/upload_creator.rb:64:in `create_for'
         8: from /home/nodebb/discourse/lib/distributed_mutex.rb:14:in `synchronize'
         7: from /home/nodebb/discourse/lib/distributed_mutex.rb:29:in `synchronize'
         6: from /home/nodebb/discourse/lib/distributed_mutex.rb:29:in `synchronize'
         5: from /home/nodebb/discourse/lib/distributed_mutex.rb:33:in `block in synchronize'
         4: from /home/nodebb/discourse/lib/upload_creator.rb:83:in `block in create_for'
         3: from /home/nodebb/discourse/lib/upload_creator.rb:501:in `optimize!'
         2: from /home/nodebb/discourse/app/models/optimized_image.rb:181:in `ensure_safe_paths!'
         1: from /home/nodebb/discourse/app/models/optimized_image.rb:181:in `each'
/home/nodebb/discourse/app/models/optimized_image.rb:182:in `block in ensure_safe_paths!': Discourse::InvalidAccess (Discourse::InvalidAccess)

@enigmaty Ich habe den gleichen Fehler wie @OdysLam @FreeWorLD.

Hallo zusammen!
Hat schon einmal jemand versucht, von der neuesten NodeBB 4.9.x auf die aktuelle Discourse-Entwicklungsumgebung zu migrieren?

/home/dev/discourse/script/import_scripts/nodebb/mongo.rb:100:in 'NodeBB::Mongo#post': undefined method '[]' for nil (NoMethodError)

      post["timestamp"] = timestamp_to_date(post["timestamp"])
                                                ^^^^^^^^^^^^^
        from /home/dev/discourse/script/import_scripts/nodebb/mongo.rb:95:in 'block in NodeBB::Mongo#posts'
        from /home/dev/discourse/script/import_scripts/nodebb/mongo.rb:95:in 'Array#map'
        from /home/dev/discourse/script/import_scripts/nodebb/mongo.rb:95:in 'NodeBB::Mongo#posts'
        from script/import_scripts/nodebb/nodebb.rb:413:in 'block in ImportScripts::NodeBB#import_posts'
        from /home/dev/discourse/script/import_scripts/base.rb:943:in 'block in ImportScripts::Base#batches'
        from <internal:kernel>:168:in 'Kernel#loop'
        from /home/dev/discourse/script/import_scripts/base.rb:942:in 'ImportScripts::Base#batches'
        from script/import_scripts/nodebb/nodebb.rb:412:in 'ImportScripts::NodeBB#import_posts'
        from script/import_scripts/nodebb/nodebb.rb:52:in 'ImportScripts::NodeBB#execute'
        from /home/dev/discourse/script/import_scripts/base.rb:47:in 'ImportScripts::Base#perform'
        from script/import_scripts/nodebb/nodebb.rb:568:in '<main>'

Ich erhalte diesen Fehler während der Migration in der Entwicklungsumgebung.
Irgendwelche Ideen?

Werden Migrationsskripte von der Community im Jahr 2026 noch unterstützt?
Das Feld timestamp existiert und enthält gültige Daten

Danke.

[quote=“Twissell, post:17, topic:126553”]'NodeBB::Mongo#post': undefined method '[]' for nil

  post["timestamp"] = timestamp_to_date(post["timestamp"])

[/quote]

Das Problem ist, dass post nil ist. Sie haben die Dinge also nicht richtig konfiguriert. Wurden Benutzer importiert?

Wir können es versuchen, aber es ist ziemlich begrenzt. Wahrscheinlich müssen Sie verstehen, wie eine Reihe von Dingen funktionieren, die über das hinausgehen, was in einem Forum leicht unterstützt werden kann.

3 „Gefällt mir“
Benutzer werden importiert
      182 / 182 (100,0 %)  [437953 Elemente/Min]
Benutzer zu Gruppen hinzufügen...

Themen werden importiert...
      132 / 132 (100,0 %)  [3567036 Elemente/Min]
Beiträge werden importiert...
/home/dev/discourse/script/import_scripts/nodebb/mongo.rb:100:in `NodeBB::Mongo#post': undefined method `[]' for nil (NoMethodError)

      post["timestamp"] = timestamp_to_date(post["timestamp"])
                                                ^^^^^^^^^^^^^
        from /home/dev/discourse/script/import_scripts/nodebb/mongo.rb:95:in `block in NodeBB::Mongo#posts'
        from /home/dev/discourse/script/import_scripts/nodebb/mongo.rb:95:in `Array#map'
        from /home/dev/discourse/script/import_scripts/nodebb/mongo.rb:95:in `NodeBB::Mongo#posts'
        from script/import_scripts/nodebb/nodebb.rb:413:in `block in ImportScripts::NodeBB#import_posts'
        from /home/dev/discourse/script/import_scripts/base.rb:943:in `block in ImportScripts::Base#batches'
        from <internal:kernel>:168:in `Kernel#loop'
        from /home/dev/discourse/script/import_scripts/base.rb:942:in `ImportScripts::Base#batches'
        from script/import_scripts/nodebb/nodebb.rb:412:in `ImportScripts::NodeBB#import_posts'
        from script/import_scripts/nodebb/nodebb.rb:52:in `ImportScripts::NodeBB#execute'
        from /home/dev/discourse/script/import_scripts/base.rb:47:in `ImportScripts::Base#perform'
        from script/import_scripts/nodebb/nodebb.rb:568:in `<main>'

Benutzer scheinen laut Skriptausgabe korrekt importiert worden zu sein, siehe oben.

Entschuldigung, sind Sie ein lebender Mensch oder nur ein kluger KI-Assistent?

Dann liegt das Problem darin, dass die Beitragsdaten nicht gelesen werden.

Ich vermute, es liegt hier und aus irgendeinem Grund findet es die Beiträge nicht.

    def posts(offset = 0, page_size = 2000)
      post_keys = mongo.find(_key: "posts:pid").skip(offset).limit(page_size).pluck(:value)

      post_keys.map { |post_key| post(post_key) }
    end

Ich bin ein lebender Mensch, der seit einem Jahrzehnt seinen Lebensunterhalt mit der Unterstützung von Discourse verdient und eine Reihe von Importern geschrieben und über hundert Foren von verschiedenen anderen Plattformen importiert hat.

Wenn Sie Hilfe von einem KI-Assistenten wünschen, besuchen Sie https://ask.discourse.com/

6 „Gefällt mir“

Irgendwie habe ich es geschafft, dass die Skriptfunktion richtig funktioniert.

Hier sind meine Änderungen (mit ein wenig Hilfe von einem Claude Code :slight_smile:)

 	>mongo.rb
   
   def posts(offset = 0, page_size = 1000)
      post_keys = mongo.find(_key: "posts:pid").skip(offset).limit(page_size).pluck(:value)
      post_keys
          .map { |pid| post(pid) }
          .compact  # <-- verwirft alle nil-Ergebnisse (verwaiste pids)
      post_keys.map { |post_key| post(post_key) }
    end

    def post(id)
    post = mongo.find(_key: "post:#{id}").first
    return nil if post.nil? # <-- Null-Prüfung
    post["timestamp"] = timestamp_to_date(post["timestamp"])
    if post["upvoted_by"] = mongo.find(_key: "pid:#{id}:upvote").first
        post["upvoted_by"] = mongo.find(_key: "pid:#{id}:upvote").first[:members]
      else
        post["upvoted_by"] = []
      end

      post["pid"] = post["pid"].to_s
      post["deleted"] = post["deleted"].to_s

      post
    end
	
>nodebb.rb

 create_posts(posts, total: post_count, offset: offset) do |post|
        # überspringe, wenn post null ist
		# überspringe, wenn es merged_post ist
        next if post.nil?
        next if @merged_posts_map[post["pid"]]

        # überspringe, wenn es gelöscht ist
        next if post["deleted"] == "1"

        raw = post["content"]
        post_id = "p#{post["pid"]}"

        next if raw.blank?
        topic = topic_lookup_from_imported_post_id("t#{post["tid"]}")

        unless topic
          puts "Topic with id #{post["tid"]} not found, skipping"
          next
        end	

Es scheint jetzt auf die richtige Weise zu funktionieren.

Obwohl ich nicht weiß, wie korrekt dies aus der Sicht der internen Architektur von Discourse ist, scheint es auf den ersten Blick zu funktionieren.

Jeder Vorschlag zur Verbesserung und Optimierung ist herzlich willkommen.

1 „Gefällt mir“

Tipp: Lass es nicht komplett stillschweigend fehlschlagen – ändere dies in

if post.nil?
  puts "!!! Could not find post #{id}"
  return nil
end

Andernfalls wirst du dich fragen, warum die Hälfte deiner Beiträge fehlt, und nach stundenlanger Frustration stellst du fest, dass es daran liegt.

Dasselbe gilt für diese beiden

        next if post.nil?
        next if post["deleted"] == "1"
5 „Gefällt mir“